Hitachi AirCore 700 Operation Installation Maintenance Manual page 12

1. Safety Summary
aging or continual vibration from sources such as compressors or fans.
•
Under no circumstances shall potential sources of ignition be used in the searching for or detection
of refrigerant leaks. A halide torch (or any other detector using a naked flame) shall not be used.
•
Air-tightness test shall be carried out as guaranteed. Charging oxygen, acetylene or other
inflammable and toxic gases during leakage inspection and air-tightness test may lead to explosions.
It recommended to use nitrogen gas for this test.
•
The following leak detection methods are deemed acceptable for all refrigerant systems.
○ Electronic leak detectors may be used to detect refrigerant leaks but, in the case of flammable
refrigerants, the sensitivity can be inadequate, or can need re-calibration. (Detection equipment
shall be calibrated in a refrigerant-free area.) Ensure that the detector is not a potential source
of ignition and is suitable for the refrigerant used. Leak detection equipment shall be set at a
percentage of the LFL of the refrigerant and shall be calibrated to the refrigerant employed, and the
appropriate percentage of gas (no more than 25 %) is confirmed.
○ The fluid used in leak detection is applicable to most refrigerants. But do not use chloride solvents
to prevent the reaction between chlorine and refrigerants and the corrosion of copper pipeline.
○ If a leak is suspected, all naked flames shall be removed/extinguished.
○ If a leakage of refrigerant is found which requires brazing, all of the refrigerant shall be recovered
from the system, or isolated in a part of the system remote from the leak. Removal of refrigerant
shall be according to this manual.
•
When breaking into the refrigerant circuit to make repairs – or for any other purpose – conventional
procedures shall be used. However, for flammable refrigerants it is important that best practice is
followed since flammability is a consideration. The following procedure shall be adhered to:
○ safely remove refrigerant following local and national regulations;
○ evacuate;
○ purge the circuit with inert gas;
○ continuously flush with inert gas when using flame to open circuit;
○ open the circuit.
•
The refrigerant charge shall be recovered into the correct recovery cylinders.
•
Purging of the refrigerant circuit shall be achieved by breaking the vacuum in the system with inert
gas and continuing to fill until the working pressure is achieved, then venting to atmosphere, and
finally pulling down to a vacuum. This process shall be repeated until no refrigerant is within the
system. The system shall be vented down to atmospheric pressure to enable work to take place.
•
Ensure that the outlet of the vacuum pump is not close to any potential ignition sources and that
ventilation is available.
•
In addition to conventional charging procedures, the following requirements shall be followed.
○ Ensure that contamination of different refrigerants does not occur when using charging equipment.
Hoses or lines shall be as short as possible to minimise the amount of refrigerant contained in them.
○ Cylinders shall be kept in an appropriate position according to the instructions.
○ Ensure that the refrigerating system is earthed prior to charging the system with refrigerant.
○ Label the system when charging is complete (if not already labelled).
○ Extreme care shall be taken not to overfill the refrigerating system.
•
Prior to recharging the system, it shall be pressure-tested with the appropriate purging gas. The
system shall be leak-tested on completion of charging but prior to commissioning. A follow up leak
test shall be carried out prior to leaving the site.
•
Before carrying out the decommissioning procedure, it is essential that the technician is completely
familiar with the equipment and all its detail. It is recommended good practice that all refrigerants
are recovered safely. Prior to the task being carried out, an oil and refrigerant sample shall be taken
in case analysis is required prior to re-use of recovered refrigerant. It is essential that electrical power
is available before the task is commenced.
○ Become familiar with the equipment and its operation.
○ Isolate system electrically.
○ Before attempting the procedure, ensure that:
(a) mechanical handling equipment is available, if required, for handling refrigerant cylinders;
(b) all personal protective equipment is available and being used correctly;
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